1. Field of the Invention
The invention relates to a processor-controlled data input and output device and, more particularly, to such a device which assigns information deriving from a signal transducer or transmitter to the input and/or output data and has at least one memory. Such a device is especially suitable for detecting the position and/or change in position of material to be printed relative to the angular position of a cylinder or a rotary printing press.
From printing press technology, it is generally known, with respect to sheet-fed rotary presses, to monitor a sheet, which is grasped by a gripper system arranged in a longitudinal slot formed in a sheet-guiding cylinder of a rotary printing press, in terms of the position of the sheet at the point of transfer relative to the angular position of the cylinder. This monitoring is accomplished with a conventional detection device which scans the leading and/or trailing edge of the sheet. If there is a deviation between the instant of sheet transfer and the angular position of the cylinder which lasts longer than a predetermined tolerance limit, the sheet will then change its position on the cylinder relative to its normal or original position. This can have a negative effect upon the printing process. If this change in position is known, the following processing stations can be apprised thereof and can take suitable counter measures. The scanning of the sheet causes data to be outputted by the detection device, and provision may especially be made that when a sheet is not present, as compared with the detection of a sheet, a change in the data occurs. If the data are delivered to the conventional processor-controlled data input and output device, the reaction to such a change in data is dependent upon the reaction time of the processor. Thus, changes in input data are normally recognized by so-called polling interrogations or queries made to the input or inputs by the processor. If position information regarding the sheet-guiding cylinder is then to be assigned to the data change at the instant of change, the data of the data input and output device present at the instant of change must be supplied together with the data change and processed instantaneously thereat. In this regard the data originates, for example, from a signal transducer or transmitter which is entrained by or rotates with the sheet-feeding cylinder. The output of a data change is also obtained by polling.
To achieve great accuracy with respect to the coordination of the instant of sheet transfer and the angular position of the cylinder, or if several inputs and outputs, respectively, of data in brief succession are necessary, the reaction time of the processor, in the case of high-speed rotary presses, is insufficient. In order to shorten the reaction time to such input and output changes of data, respectively, it has become known heretofore to use alarm inputs or so-called interrupts. These interrupts are not always made available for the desired requirements, however, or may be interrupted themselves by other higher-priority interrupts. Accordingly, the problem has not been solved satisfactorily.
One possible but rather expensive alternative is to use a plurality of processors.